Biology (Cell Division)

GREASE THOSE WHEELS ( BIOLOGY )

#4 CELLULAR and NUCLEAR DIVISION

> explain the importance of mitosis in growth, repair and asexual reproduction;

explain the need for the production of genetically identical cells and fine control of replication;

explain how uncontrolled cell division can result in cancer and identify factors that can increase the chances of cancerous growth;

describe, with the aid of diagrams, the behavior of chromosomes during the mitotic cell cycle and the associated behavior of the nuclear envelope, cell membrane, centrioles and spindle (names of the main stages are expected);

explain the meanings of the terms haploid and diploid and the need for a reduction division prior to fertilization in sexual reproduction;

------------------------------------------------------------------------------------------------------------------------

Every wondered why, after getting a nasty cut, you skin grows back. Ever thought out about the stuff thats going that results in your hair getting longer day by day? No? Well then you are not aware of nature's most important process that lets almost everything grow, reproduce and survive...Cell Division; and at our level...Mitosis!

------------------------------------------------------------------------------------------------------------------------

Mitosis is a five step process, followed by cytokinesis, that helps cells divide to two similar daughter cells. It only involves somatic or normal body cells and not gametes. Mitosis is important because...

It aids simpler organisms, like bacteria, to reproduce asexually.

It allows regeneration of damaged or worn out body tissue.

It also aids us in growth as our cells multiply and we become multicellular organisms after conception.

Moreover the formation of healthy daughter cells from mitosis tells about the non-problematic state our genome because the daughter cells have the same genetic material as the parent cells.

Before a cell can divide, there is a combination of phases in its life cycle known as interphase which involves...
Growth Phase 1 (G1): New organelles are formed to provide daughter cells with.
Synthesis Phase (S): DNA is replicated.
Growth Phase 2 (G2): Cell builds up its energy reserves to power mitosis.

------------------------------------------------------------------------------------------------------------------------

Although mitosis is doesn't always occur smoothly. An abnormal case of mitosis is cancer. Which is a medical condition that involves, uncontrolled growth of infected cells, invasion and destruction of adjacent healthy cells and spread to other parts of the body. It is caused by...

Carcinogenics, like cigarette smoke, harmful radiation and other chemicals that cause mutation of the human genome.

Infection with oncogenes which are viruses that affect the genes associated with normal cell division, more specifically the tumour suppressor gene.

Errors in DNA Replication can also cause cancer despite bodies seemingly tough checks.

Immune system not functioning properly can also increase the chances of cancerous growth.

Cancerous growth can also be inherited, as in breast cancer.

------------------------------------------------------------------------------------------------------------------------

Now let us look at the stages of cell division in a little more detail...

1. Prophase

• Before prophase genetic material in the cell's nucleus is in a loosely bundled, kind of a suspension form; known as chromatin. But after the onsets of prophase chromatins condense to form highly organized chromosomes which have two chromatids joined at the centre called centromere. (lots of Cs eh? =P)
• Centrosomes (pair of centrioles) migrate to opposite poles of the cell.
• Spindle fibers generate from the two centrosomes (one of them is replicated when mitosis is about to occur) upon the polymerization of soluble tubulin. The spindle fibres can be thought of as molecular pathways; about 30 nm in diameter; upon which most cellular organelles move about in the cell.

2. Prometaphase

• Nucelolus has disappeared.
• Nuclear membrane degenerates.
• Spindle-fibers invade the nuclear space attaching themselves to the centromeres of chromosomes each chromosome is attached to both the centrosomes as they lie at the opposite poles of the cell.
• Chromosomes lie are pulled by spindle-fibers to the equator of the cell.

3. Metaphase

• Chromosomes now lie at the equator of the cell.
• Contractions in the spindle-fibers (requires ATP) results in sister chromatids starting to split apart.
• Proper alignment is necessary to proceed to anaphase. Thats why cells remain in metaphase for hours and even days to make this happen.

4. Anaphase

• Sister chromatids have separated at the centromere and are migrating towards the poles marked by the centrosomes.
• First signs of cell-membrane invagination are visible.

5. Telophase

• It is basically the cancellation of the effects of prophase and prometaphase.
• Sister chromatids which had migrated to the opposite ends of the cell become surrounded by a nuclear membrane each.
• Chromosomes decondense to form chromatin.
• There are now two nuclei in the same cell; nucleolus has also reappeared.
• Spindle fibers degenerate.
• Mitosis is now complete.

6. Cytokinesis

• This the process by which a cell actually divides into two separate entities.
• Contractile ring in the centre of the cell pinches the cell inwards uptil separation.
• Cytokinesis doesn't occur in plant cells. in it a cell wall plate forms which divides the cell asymmetrically. 

Now lets look at this process as a whole...

------------------------------------------------------------------------------------------------------------------------

Biology (Genetic Control)

GREASE THOSE WHEELS ( BIOLOGY )

#3 GENETIC CONTROL

> describe the structure of RNA and DNA and explain the importance of base pairing and hydrogen bonding;

explain how DNA replicates semi-conservatively during interphase;

state that a gene is a sequence of nucleotides as part of a DNA molecule, which codes for a polypeptide;

describe the way in which the nucleotide sequence codes for the amino acid sequence in a polypeptide with reference to the nucleotide sequence for HbA (normal) and HbS (sickle cell) alleles of the gene for the β-haemoglobin polypeptide;

describe how the information on DNA is used during transcription and translation to construct polypeptides, including the role of messenger RNA (mRNA), transfer RNA (tRNA) and the ribosomes;

explain that, as enzymes are proteins, their synthesis is controlled by DNA;

------------------------------------------------------------------------------------------------------------------------

People say that genetics is a unit that simply blasts off the thought of an easy biology course. I, myself, have spoken to many-a-students who have dropped bio' for it and those who run away from the very thought of base-pairing, DNA and RNA.

Therefore, this post is dedicated to all those who think genetics is crap!!!

------------------------------------------------------------------------------------------------------------------------

Lets start with the structure of DNA and RNA.

DNA, short for deoxyribonucleic acid is the longest molecule in your body, so long that when all the DNA in your body is put together it could go to and come back from the sun nearly 102 times!!!

Lets start with its basic structure...

DNA is made up of basically these three things...

• Deoxyribose Sugar (A type of pentose aka 5-Carbon sugar, variant of ribose as it lacks O at 2' Carbon)
• Phosphates. x3 but the two break-away when phospho-diester bond forms.
• Nitrogenous Bases which include...(they are all flat structures because of being rings and thus are easily stackable in the DNA molecule which compacts the size and also strengthens the molecule)
• Purines (dual-ring structure)
• Adenine
• Guanine
• Pyrimidines (single-ring structure consisting of six sides)
• Thymine
• Cytosine

All of the above mentioned components, together build the backbone of the DNA molecule. They form nucleotides (see left) which get linked together to form a polynucleotide.

Now let us see the DNA structure in more detail...

First of all there is a single strand...

• Then the polynucleotide chain is formed which contains half the amount of sugar, phosphate groups and bases than in the final DNA molecule.
• polynucleotide arrangement is achieved by linking nucleotides together with the aid of phosphate groups. The phosphate attaches either to the 5' of one sugar and the 3' to the adjacent one or vice versa (in a phospho-diester bond that is). The former is the case with the above illustrated nucleotide and therefore the orientation of the formed polynucleotide will be from 5'-3' and the other DNA strand will be in an anti-parallel orientation of 3'-5', this kind of arrangement helps in the hydrophilic sugar and phosphate groups facing outwards and the hydrophobic bases to face inwards thus resulting in the stability of the DNA molecule by twisting it around as the sides pull the molecules in the opposite direction.

Then its mate shows up...

• both the polynucleotides join in an anti-parallel arrangement with complimentary base pairing. The hydrogen bonds between adenine-thymine and guanine-cytosine link the strands together.

Anti-parallel structure of DNA. The red/white molecule is the OH on the 3' of deoxyribose. While the orange\red molecule if the Phosphate one, attached to the 5' of ribose.

Complimentary Base arrangement in DNA. Cytosine-Guanine (left) and Adenine-Thymine (right). White, broken lines show hydrogen bond.

Some important points in a DNA's arrangement are...

• Hydrogen bond, although relatively weak when compared to covalent bonds, become a strong force when occurring between millions of base pairs. This confers stability on the vital DNA molecule and helps it stay together. Hydrogen bonds also aid in the formation of the dual-helix structure of DNA. Their weak nature also helps in the easy unzipping of the two strands of DNA when required.
• Accurate base-pairing is essential in a DNA molecule as an alteration in these would result in mutations that several affect a living organism. Each combination of nucleotides is a gene codes for a specific polypeptide and thus changes in these would result in a wrong polypeptide being encoded.

------------------------------------------------------------------------------------------------------------------------

Now lets get to the RNA...short for ribonucleic acid; it is a single strand molecule that never has thymine but has uracil instead. It also contains ribose sugar instead of deoxyribose sugar in its nucleotides. There are three main types of RNA in our body.

• Messenger RNA (mRNA) is formed in the nucleus as a mirror image of a strand of DNA, except that thymine is replaced by uracil. It is a alpha-helical in structure and acts as a template for protein synthesis.
• Transfer RNA (tRNA) is also formed in nucleus from about 80 nucleotides and has a clover-leaf shape. Its main role is to fetch amino acids for protein synthesis and has specificity for them thus about 20 types of tRNAs exist for the twenty amino acids in nature.
• Ribosomal RNA (rRNA) is the central component of our protein manufacturing factories, i.e, ribosomes. It is the largest of the RNAs and can also exist in dual-helical form. Its main function is the decoding of the mRNA molecule and interaction with the tRNA the results in a polypeptide being formed.

------------------------------------------------------------------------------------------------------------------------

Over with the structures now let us get to some factory work!!!

1st Process....REPLICATION....
The Crew....

• Initiator Proteins: provide origin for replication by forming a replication bubble or opening.
• Helicase: unzips or opens up the DNA strand.
• SSB: or single-strand-binding proteins temporarily bond with the DNA strands to prevent them from recombining.
• Gyrase: prevents knotting in the DNA open. molecule
• Primase: lays down primers so that replication can initiate.
• DNA Polymerase: it is the main player in DNA replication and is an enzyme complex that carries out the following functions...
• Adding of nucleotides.
• Replacing RNA Primers with DNA.
• Proofreading.
• Ligase: seals the gaps on the lagging strand.

The process...

1. Initiator protein scoots along the DNA molecule until it comes across a specific base combination. it stops there and creates a small opening.
2. Helicase then finds that opening and unzips the DNA molecule into two strands by breaking the hydrogen bonds, forming a replication fork, or a horizontal Y in the DNA molecule.
3. SSB proteins then bind with the separated strands so that they don't recombine again.
4. Gyrase prevents the knotting over of the coiled DNA molecule as in a separated state, it has a real tendency to disrupt our genetic code.
5. As for a new strand to begin some foundation should be laid to construct over, i.e, a reactive OH tail at 3' of the deoxyribose sugar should be present so that a polynucleotide can form from it. So as the new strand is completely naked i.e has nothing to support the formation of a new strand, primers (RNA nucleotide) is laid by the enzyme RNA primase to get the process rolling. However there is a complex situation involved. DNA Polymerase can only add deoxyribonucleotides (a fancy way to say, DNA's nucelotides) in the 5'-3' direction or in other words only to a free 3' OH tail; this results in a leading and lagging strand. The leading strand being where DNA polymerase keeps on adding ribonucleotides in the 5'-3' direction continuously after an initial primer is placed. The lagging strand being the one where addition of ribonucleotides occurs in breaks called, Okazaki fragments, which are around 200-300 nucleotides long and polymerase stops when it encounters 5' of another fragment.  It is a difficult concept, I know, therefore lets have a look at the diagram below.
6. Ligase fills the gaps between the fragments. As DNA polymerase replaces the RNA primers with DNA.
7. Finally proof-reading is done by DNA Polymerase in 3'-5' direction.

------------------------------------------------------------------------------------------------------------------------
2nd Process...TRANSCRIPTION....
The Crew....

1. RNA Polymerase: does the same work as DNA Polymerase in the earlier section but has only two fundamentally different functions than the DNA Polymerase...
• Uracil is used instead of thymine.
• Usage of ribonucleotide instead of deoxyribonucleotide in polynucleotide assembly.
2. Holoenzyme: is a group of enzymes that look up the gene to be transcribed for the RNA Polymerase.

The Process....

1. Holoenzyme finds the promoter sequence for RNA Polymerase. It is usually known as the TATA Box and is on the non-template strand (the one to be transcribed); the promoter tells RNA Polymerase that how many bases away is the base sequence of the gene to be encoded.
2. After Holoenzyme has found the promoter gene; it signals RNA Polymerase to come over and begin the task of transcription.
3. RNA Polymerase first melts the hydrogen bonds between the two strands so that the region to transcribe can be viewed.
4. When the template strand (the one that is not transcribed but serves as a template to form the non-template strand) is exposed. RNA Polymerase starts laying down ribonucleotides which have bases complimentary to the template strand without the need of a primer.
5. The elongation of the mRNA strand proceeds in the 5'-3' direction until the terminator sequence is encountered by the DNA Polymerase upon which it transcribes the terminator sequence and halts transcription.
6. It detaches itself from the template strand.
7. A 5' Cap of Guanine is added to the mRNA molecule with some methyl groups that prevent decomposition and deem the mRNA molecule ready for translation.
8. A 3' Tail of Adenine is attached at the end of the mRNA molecule, again to prevent decomposition form nucleases as mRNA is temporary so nucleases start destroying it the moment it steps into the cytoplasm so the addition of tails means that the message stays long enough to be translated by ribosomes.
9. Intorns (non-encoding)are removed from the mRNA molecule so that only Exons (encoding) remain.

------------------------------------------------------------------------------------------------------------------------

3rd Process...TRANSLATION....

The crew...

• mRNA: serves as the template for translation.
• Amino Acids: they are linked together to form a protein.
• tRNA: provides courier service during the process by fetching the amino-acids required.
• Ribosomes: provide the frame-work for the occurring of the process.

The process...

1. mRNA moves out into the cytoplasm.
2. tRNA have their complimentary amino acid hooked to the acceptor / 3' arm by aminoacyl synthetases who recognize the anti-codon on the tRNA molecule.
3. The two subunits of Ribosomes come together, the smaller subunit binds to the 5' end of the mRNA molecule.
4. Codon (group of three bases) on the mRNA molecule attract their complimentary anticodons on the tRNA molecule. The ribosome unit that is travelling along the mRNA strand allows the incoming complimentary tRNA molecules to fit in; two at a time, when the two tRNA molecules are held in close proximity, then the amino acids on their 3' arms combine to form a peptide bond and thus a polypeptide forms as the chain grows.
5. Many ribosomes work on the same tRNA molecule to give many copies of the protein transcribed on the mRNA molecules.
6. When the terminator sequence is reached by the ribosome, then translation stops as there is no anticodon for it.

Structure of tRNA

...CODON TABLE...

------------------------------------------------------------------------------------------------------------------------

One of the most common anomalies associated with wrong base sequence, is none other than the sickle-cell anaemia. Lets journey to the core of this disease.

Name: Sickle-Cell Anaemia 

Affected body-parts: Blood Tissue \ RBCs

What it does?: This genetically inherited disease alters the shape of the RBC; from flattened biconcave disks to crescent or sickle shaped. This reduces the amount of oxygen they can carry and also makes them 50-times less soluble in blood upon deoxygenation which can result in the cells being precipitated.

Symptoms: Body Ache, Lethargy, Pale Skin.

Cause: Normally our Hemoglobin (HbA) has four polypeptide chains (alpha, beta, delta and gamma) which combine with 4 haem groups. But in sickle cell patients, due to wrong base grouping, valine (see above, its an amino acid) replaces glutamine (see above) at the 6th position in the beta-polypeptide chain, such small a change can lead to such drastic effects. But this disease shows in up in only homozygous form, i.e, when both the genes you got from your parents code for sickle cell RBCs. In hetrozygous form, you can only have a sickle-cell trait but, luckily, not the disease!!

Prevention: No preventive measure known.

Medication: Pain-relieving medicines, Hydrea, Droxea, Blood Transfusions, Supplemental Oxygen, Bone-Marrow transplant, Nicosan.

Special Fact: Reduced susceptibility to the malarial parasite.

------------------------------------------------------------------------------------------------------------------------

Biology (Ecology)

GREASE THOSE WHEELS ( BIOLOGY )

#2 ECOLOGY

• define the terms habitat, niche, population, community and ecosystem and state examples of each;
• explain the terms producer, consumer and trophic level in the context of food chains and food webs;
• explain how energy losses occur along food chains and discuss the efficiency of energy transfer between trophic levels;
• describe how nitrogen is cycled within an ecosystem, including the roles of microorganisms;

------------------------------------------------------------------------------------------------------------------------

Many students often describe ecology as the most easiest part of any biology course and I agree with them because ecology is nothing more than memorizing key definitions and remembering them at the time of need with a few exceptions like nitrogen and carbon cycles...

and so we will get over with this in the same method...

------------------------------------------------------------------------------------------------------------------------

Lets start with all the important definations that you should know...

• Ecology is the study of living organisms and their relationship with all the other biotic (living) and abiotic (non-living) components of their environment.
• Environment are the external conditions, resources and stimuli with which organisms interact which in turn affects their survival, life and growth.
• Species are a group of organisms that are reproductively isolated, inter-breed within themselves to produce fertile offsprings and have structural similarities between them that results in them being told apart from other species.
• Habitat is a Latin word for it inhabits and is defined as an ecological area that is inhabited by a population or an organism which is characterized by its dominant producer or physical features. For example, grasslands, alps etc.
• Population is the collective name given to all the organisms of a particular species within a particular area at a given time. They share the same gene pool and are usually isolated from other populations of the same species. For examples the Tigers of central Bengal are a population.
• A niche is a functional role of a specie or population within an ecosystem, i.e, its way of interacting with other biotic and abiotic factors of its environment. For example, a shoal of fishes are a niche in an aquatic habitat, because they interact with other factors and play their part in the ecosystem like providing food to the sharks (prey), feeding over plankton (eating), reproducing within themselves to increase the size of the population etc.
• Community is basically an expanded defination of population as it is the collective name given to all populations of different species that inhabit a particular area at a given time. For example camels, foxes, scorpions etc living in the Sahara are a community.
• Ecosystem is defined as a unit in which all biotic and abiotic factors interact with each other during their normal function and is characterized by an energy flow through the chain of organisms. Examples can be, an ocean, a rain-forest or even a decomposing log!
• Producers are the auto-trophic organisms, like plants, who initiate a food chain because of their ability to produce energy rich organic compound from simple inorganic compounds, like water and carbon dioxide, and energy from sunlight.
• Consumers are hetero-trophic organisms that obtain their food form other organisms by eating or decomposing them.
• Decomposers are sapro-trophic organisms that feed on dead and decaying organisms and organic waste. They play an important part in nutrient recycling.
• Trophic Level is the position on which an organism feeds in a food chain. It can be trophic level 1 for producers, 2 for herbivores, upto 5 for predators and no place for decomposer.

Thats it for the definitions part...now lets move on to the other components...

------------------------------------------------------------------------------------------------------------------------

The concept of energy losses should be mastered before sitting for your AS Level examination as it is one of the most frequently  tested concepts.

Food chains cannot be simply put as transfer of food from one living thing to another, for example not all the energy a hen produces is transfered to your chicken roast!!, it involves energy losses as some energy is utilized by the organism for...

• Respiration (energy expended by consumers is larger than the producers due to their increased activity)
• Excretion (exhalation and excretion)
• Death and decaying of the organism.
• Heat Energy due to activity.

------------------------------------------------------------------------------------------------------------------------

Nitrogen Cycle is an important part of the ecosystem because nitrogenous compounds help the growth and survival of almost all living organisms, as nitrogen is a component of almost all amino acids and subsequently all proteins, RNA and the most important of all the DNA. But the problem is that atmospheric nitrogen (N2) is  not usable by living organisms for the above listed functions so nitrogen fixation is as important a process as nitrogen itself. Lets look into this crucial-for-life cycle and its processes.

• Nitrogen-fixing bacteria forming symbiosis (an ecological partnership) with a legume plant. It resides in the root modules of the plant and gets food and shelter from the plant while rhizobium (a type of nitrogen-fixing bacteria) provides th plant with organic nitrogen compounds such as glutamines (first of all it converts atm. nitrogen to ammonia).
• Another type of Nitrogen fixation occurs in the soil where bacterias like azotobacter convert atmospheric nitrogen to more reactive forms of nitrogen. Nitrogen fixation also occurs in some other ways..
• Via the Haber Process, when ammonia is made from hydrogen and nitrogen under high temperature and pressure. The subsequent use and manufacture of fertilizers and other chemicals helps in nitrogen fixation.
• Lightning is another source of fixed nitrogen.
• Oxides of nitrogen releases by internal combustion engines.
• Ammonification is basically the conversion of nitrogenous wastes or dead animals or plants back into ammonium ions. It is done by both aerobic or anaerobic bacteria and in some cases fungi.
• Nitrification is the conversion of ammonium ions into nitrates and nitrites; usually in two steps...
• Nitrosomonas convert ammonium ions to nitrites (NO2-). As accumulation of nitrites is toxic for plants so it must be quickly converted to nitrates.
• Nitrobacter converts nitrites in to highly soluble nitrates (NO3-).
• Bacteria species like Clostridium convert nitrates back to inert atmospheric nitrogen, in a process called Denitrification, thus completing the nitrogen cycle. They do this by using nitrates as the electron acceptor in place of oxygen in their respiration cycle.

------------------------------------------------------------------------------------------------------------------------

Thats all! Hoping that it was of some use to you!!

Economics (Inflation)

GREASE THOSE WHEELS (ECONOMICS)

#3 UNEMPLOYMENT

• Employment Statistics
• Size and components of labour force
• Labour productivity
• Definition of unemployment
• Unemployment rate; patterns and trends in (un)employment
• Difficulties involved in measuring unemployment

------------------------------------------------------------------------------------------------------------------------

Unemployment? We all are familiar with this word, living in today's world, but have you ever tried to get deeper into this stuff; like what causes it and what are its consequences. No? I was expecting that! So lets just explore this phenomenon which we hear about almost everyday!!

------------------------------------------------------------------------------------------------------------------------

First of all we should know as to how we measure via the employment statistics the rate of unemployment in a country. Simple...

1. The total civilian labour force (people who are aged 16 or above and are employed or actively searching for unemployment) is determined.
2. Next the number of unemployed persons is determined (the people who are actively looking for jobs or have not worked for more than an hour in the week before the survey was conducted)
3. Exclusion of people who are employed by the military, have a long term illness or are voluntarily unemployed.
4. Unemployed Persons / Total Civilian Labour force x 100 = Unemployment Rate.

The above figure showing the unemployment rates of the U.S shows that unemployment is a dynamic concept and keeps on changing with time as more people come of working age and start finding jobs or get jobs along with other people who lose their jobs. So at a given time if more people get jobs and lesser people lose their jobs, the rate of unemployment will drop, and vice versa.

Some 'jumps' in the above graph are explained...

• 1929 and onwards was the Great Depression the period of great economics instability around the globe. Revenues dropped for firms and so they started striking off people from their factories.
• 1945 was the year when the U.S went all out in war against the Nazis, more of everything was required in the country, more ammunition, more food and more clothing. Thus as a result unemployment dropped (people became self employed as well) to an all time low as America coped with the war and the GNP almost doubled.
• 1970-71, 1974-75, 1980-81, 1983-84, 1991-92, 2003-04 were all recession years in the U.S economy.
• In 2008 another period of economic recession hit the world and unemployment is increasing and expected to increase.

Additionally unemployment is also very difficult to measure because...

• Data collection may not be accurate or may be subjected to mathematical errors or a wrong response from the people surveyed.
• Some people of working age may not prefer to work due to family business or other causes.
• Data collection is very time-consuming and expensive.
• People might disguise their unemployment.
• They dynamic nature of unemployment makes it difficult to keep track of so many changes.
• frictionally and casually unemployed portion of the labour force is difficult to measure.

------------------------------------------------------------------------------------------------------------------------

Now let us look at the costs and effects of unemployment...

• Total economic output decreases, i.e the GDP, (as it is the next best alternative) as the available manpower decreases. It is known as the GDP gap and is shown as the distance between a point inside a PPF and a point on the PPF.
• Unemployed people's benefits also put an extra burden on the governement.
• Increase in the Misery Index which is also known as the discomfort index which is the sum of the rates of inflation and unemployment and depicts the suffering of an individual.
• The uncertainity that lurks when unemployment exists severely hinders economic growth, as worker insecure about their jobs do not make some buyings which results in decreased revenues for firms and thus they start increasing prises, contributing to inflation. Government also reduces spending on social welfare projects like construction of roads etc as it is unsure about the tax revenues it will get.
• Loss of revenue to the governemnt in the form of decreased income taxes and national insurance.
• Economic instability also contributes to the political instability of a nation. For example a government that has failed to cope with unemployment and other economics vices is tagged as useless and an average voter starts to look for changes. Bill Clinton's victory over George Bush in the 1992 elections is largely contributed to the recession of 1991.
• Loss of self confidence of the individual.
• Increased crime rates, family break-ups, suicides and other social vices.

------------------------------------------------------------------------------------------------------------------------

Now let us look at the different sources of unemployment that exist on this planet of ours...=P

• Frictional Unemployment is caused by people quitting one job and looking for another one, in other words, when workers are between jobs. This is usually for a short period of times. As long as freedom of choice exists for workers, there always be some frictional unemployment.
• Structural Unemployment results from economic growth, changes in consumer tastes or any other factor that changes the way an economy operates and thus reduces the demand for some workers. It may also be due to outsourcing (the hiring of foreign firms to carry out not-that-important functions for a local company like customer support, availability of technical support, an example is the Hewlett-Packard Company. It is mostly done to lower operational costs). Some examples are...via economic growth; the advent of automobiles resulted in a decreased demand for horse-carriage makers and they went out of business due to structural unemployment, via changes in customer's tastes, popularity of Toyota automobiles resulted in structural unemployment in the U.S company, Ford, via the government, the 1990 closure of many military bases resulted in structural unemployment.
• Technological Unemployment occurs when simply put, machine take over the work from workers. Thus making the worker's skills obsolete. Since the advent of computers such unemployment had been steadily on the rise. Although some say it should be linked with the structural unemployment bu the magnitude of the two unemployments keep them apart with technological unemployment not on that large scale as structural unemployment goes on. Examples can be of proof-readers as spell-checking programs appeared, database managers as database managing programs appeared.
• Cyclical Unemployment is related to swings in the business cycle that forces firms to put off some workers until economic conditions improve, which is usually after several years. Economic instability such as recession usually results in millions of jobs being lost and is an example of cyclical unemployment.
• Seasonal Unemployment results from changes in demand for a specific type of workers at regular intervals or at fixed times every year. Example can be of crop-harvesters who are required in under-developed countries like India when the season of crop harvest arrives and are unemployed for most of the year.

------------------------------------------------------------------------------------------------------------------------

Labour productivity is another examiner favourite when talking about MCQs...here are some facts to remember...

• It is given by the formula Total Output/Total Employed Workers x 100.
• It is a measure of quantity of good produced by one worker in a firm.
• Here are some factors that affect labour productivity.

• Experience...the more the experience the more the productivity.
• Attitude towards the job...if it is loyal then increased productivity but if it is that of burden and half-heartedness then lesser the productivity.
• Wages; the lower the wages the lower the productivity and vice versa.
• Attitude of supervisor. It matters a lot if it is encouraging then good going, but when it gets overly bossy then......=P
• The use of newer technology.
• The facilities provided to workers.

------------------------------------------------------------------------------------------------------------------------

Thats all from this topic....see you later with some other boring component of your syllabus...=PP

Economics (Trade-2)

GREASE THOSE WHEELS (ECONOMICS)


#2 ABSOLUTE and COMPARATIVE ADVANTAGE

• Principles of absolute and comparative advantage, and their  real-world limitations
• Other explanations/determinants of trade flows
• Opportunity cost concept allied to trade

------------------------------------------------------------------------------------------------------------------------
Trade and specialization is necessary for everyone to be better off...think about a world where there is no specialization and no trade between countries...then you will have to grow your own food, make [!] your own hairgels, you would ever have a feel of CK Jeans, Harley Davidsons would just remain to pictures and Toyota would have been localized to Japan only. I think you are starting to see the benefits of trade...=P!!
Some well known facts about trade are...

• Trade occurs only when both the parties are benefited.
• Trade involves importing and exporting of goods.

------------------------------------------------------------------------------------------------------------------------

Now lets move to the very important question that why do countries trade??

The answer is simple, nations trade so that they can get goods from other countries that are more expensive to produce at home and meanwhile focus their resources on good they specialize in and then sell them to the world.

So the boil down of the above mentioned reason is that nations trade because of specialization. Nations produce goods that they produce efficiently and trade them for goods that they are not good at producing [tongue twister, anyone? =P]. For example Kenya specializes in the production of tea by focusing its resources on it and then trades it with nations like France who are less efficient at producing tea for other goods like packaging machinery which they are not that efficient at producing.

So we can safely say that specialization is the heart and soul of international trade.

Moving on to the concept of absolute advantage.

It is defined as a country's ability to produce more of a good or service than another country.

Before we look at it we should see the system's assumptions first.

• Transportation costs are zero.
• There is no imposition of tariffs or custom duties on the import of that good.
• Prices are to remain constant.
• There are only two countries X and Y in the world.
• There are only two goods produced in the world.

For example we draw the PPFs of two countries Alpha and Beta and both of them produce two goods mangoes and oranges...

Before specialization...Alpha produces 10 mangoes and 15 oranges. While Beta produces 20 mangoes and only 10 oranges but afterwards both the countries specialize in the production of the fruit they are good at and so Alpha produces 25 oranges now and 0 mangoes while Beta produces 30 mangoes and 0 oranges and so we say that Alpha has an absolute advantage in the production of oranges while Beta has the absolute advantage in the production of mangoes.

Now let us look at the more complex comparative advantage.

It is defined as a country's ability to produce a good more efficiently or at a lower opportunity cost then other countries.

For example we again draw the PPFs of two countries Gamma and Bravo and, again both of them produce only two goods wheat and rice.

Before specialization...Gamma produces 5 tons of wheat and 10 tons of rice. While Bravo produces 20 tons of wheat and 60 tons of rice. Complex, eh? No scene of absolute advantage here so we resort to the good old concept of opportunity cost.

• Opportunity cost for Gamma on the production of a ton of wheat is (10/5) 2 tons of rice.
• While the opportunity cost for Bravo to produce a ton of wheat is (60/20) 3 tons of rice.

So Gamma has a comparative advantage on the production of wheat as it produces it more efficiently than Bravo, i.e, its opportunity cost of production of a ton of wheat is lower than that of bravo.

Now let us look at the opportunity costs for the production of a ton of rice for the two countries.

• Oppertunity cost for Gamma on the production of a ton of rice is (5/10) 1/2 tons of wheat.
• While the oppertunity cost for Bravo to produce a ton of rice is (20/60) 1/3 tons of wheat.

Here Bravo has a comparative advantage in the production of rice.
------------------------------------------------------------------------------------------------------------------------
Now let us look at it with the aid of graphs and we will then look at the advantages of specialization.

• The unbroken PPFs show the before trade scenario of production for the two countries. U.S has a comparative advantage in the production of food (as it has to give up 2 units of clothing in producing a unit of food compared to the 4 units of France). While France has a comparative advantage in the production of clothing as it has to forgo 1/4 unit of food in the production of a unit of clothing compared to the US's 1/2 unit of clothing.
• So by the law of comparative advantage France should specialize in and export clothing while the U.S should divert all its resources on the production of food and export it.
• After specialization, look at the intercepts of the PPF for the only good the country has chosen to produce. As we see U.S would make 500 units of food while France would produce 1200 units of clothing.
• Assume the terms of trade (average export price/average import price) for these goods in the international market will be 1 unit of food for 3 units of clothing (it should be less than 4, the before-trade relative price of the good so that France finds some benefit in trade) a further assumption is that a country sells all what it produces so by this France will have 1200/3 = 400 units of food (mind that 450 on the graph!...=P) more than the maximum of 300 it had before trade. While the US will have 500x3 = 1500 units of clothing, which is 500 more than the before trade, maximum quantity of that good. These changes are shown by the broken curves in the above figure, known as the consumption possibility curve.
• Look at the two graphs again, did you find out that the citizens of the two nations are better off after trade! The U.S citizens can now get 600 units of clothing along with 300 units of food (by exporting 200 units of food) which is better than the before trade situation when a U.S citizen would have gotten 600 units of clothing along with 200 units of food (by exporting 600 units of clothing). Same is the case for France.
• The imports are shown by the amount of goods a country consumes which it doesn't produce. It is 600 units of clothing for the U.S and 300 units of food for France.

From this stuff we can deduce that...

• After trade both countries will end up with more of each good.
• The terms of trade will fall between the before trade prices of the good in both the countries (it was 4 for France and 2 for the US, thus the TOT was 3).
• Total world output will increase.

------------------------------------------------------------------------------------------------------------------------

Although this theory looks quite good on paper, but in real world it has severla limitations...

• Existence of tariffs and transport costs reduces benefits from trade.
• Constant costs in real word are way to unrealistic. The more the production of a good the lower its cost should have been. So the negotiations of terms of trade gets a bit difficult.
• Governments cannot simply close down industries which they do not have a comparative advantage in due to political unrest.
• During periods of turmoil like war countries can suffer as foreign trade comes to a halt for that country as the country are too dependent on other countries after specialization.
• Some strategically important goods like weapons and steel should be produced by a country to support it during times of turmoil.
• Specialization is harmful at a great extent. For example, Saudi Arab is a country that is too dependent on oil for economic growth. Lower prices of oil can really put a halt to economic activities in  such countries so a little diversification should be there to cancel out such harmful build-ups.

------------------------------------------------------------------------------------------------------------------------

Chemistry (Ideal Gases)

GREASE THOSE WHEELS (CHEMISTRY)

#3 IDEAL GASES

• state the basic assumptions of the kinetic theory as applied to an ideal gas
• explain qualitatively in terms of intermolecular forces and molecular size:
• the conditions necessary for a gas to approach ideal behaviour.
• the limitations of ideality at very high pressures and very low temperatures.
• state and use the general gas equation pV = nRT in calculations, including the determination 
• of Mr

------------------------------------------------------------------------------------------------------------------------

Before we start off with this component of our syllabus, you should have some background knowledge about gases...

• Gases exert a pressure on the container walls they are contained in.
• Gases have very weak forces of attraction between them which allows their molecules to move about randomly, independent of each other. Which we condense into constant random motion.
• Gases can be compressed, i.e, they can be forced to consume a smaller volume upon the application of pressure.
• At constant temperature the product of pressure and volume of a gas is constant for all values of pressure and volume thus the important, Boyle's law, P1V1 = P2V2. [Remember you can use any units for calculations involving the Boyle's law unless and until both values of pressure have the same units. (the same is true for volume)]
• At constant pressure, the volume of a gas is proportional to its temperature thus Charles's Law, V=kT [T is always used in Kelvins where the relationship between degree Celsius and Kelvin Scale being: Temperature in degree Celsius + 273 = Temperature in Kelvins while any identical units for volume may be used]
• The above mentioned gas laws can be combined to give P1V1/T1 = P2V2/T2.
• The reference point for discussing changes in gas behaviour is the s.t.p (standard temperature and pressure) where temperature equals absolute zero \ 273 Kelvins and pressure equals 1 atm or 101325 Pa and volume taken as 22.4 dm3 in the light of Avogadro's law which states that all gases have the same number of molecule at equal volumes when temperature and pressure are kept constant, i.e, V = kn where n is the number of moles of the gas.

------------------------------------------------------------------------------------------------------------------------

Combining all the previously stated laws and relationships, we get the ideal gas equation.

"PV = nRT"

Where...

• P = Pressure = in Pascals (1KPa = 1000 Pascals)
• V = Volume = in metre cubed (1 m3 = 10^-3 dm3 = 10^-6 cm3)
• R = Constant = 8.71 J/mol.K
• n = number of moles of gas = in mols
• T = Temperature = in kelvin (Temperature in degree Celsius + 273 = Temperature in Kelvins)

Now you will be asking that what is an Ideal Gas hmm...well researchers from a bygone era laid down these assumptions for an ideal gases.

1. The size of a gas molecules is negligibly small and they are in constant random motion in a straight line.
2. The volume occupied by a gas molecules is negligibly small when compared to the volume of the container and gas molecules have large intermolecular distances.
3. The collisions between the walls of the container and the gas molecules and within the gas molecules are perfectly elastic, i.e, there is no net loss or gain of energy.
4. The attractive and repulsive forces between gas molecules are so weak that they should not be considered.
5. The average kinetic energy of gas molecules is proportional to the absolute temperature of the gas.

But all gases do not behave identically and usually deviate from being an ideal gas. Why? Lets see..

Non-ideal gas behaviors is especially noticeable at low temperature and high pressure. We see this in the light of two main faulty assumptions of the ideal gas theory (see text in red above)...

• At high pressures the volume of the container decreases and so the gas molecules become a considerable fraction of it so at high pressures the product PV is higher than expected for ideal gases.
• At low temperatures the average kinetic energy is way to less and the attractive forces between the gas molecules become dominant and the gas molecules strike the walls with decreasing vigor and the product PV gets lower than expected for ideal gases.

Remember! For an ideal gas the plot of PV against Pressure is a straight line and that gases with a lower Mr get more close to showing ideal gas behaviour, i.e, hydrogen is more ideal than ammonia.

------------------------------------------------------------------------------------------------------------------------

Thats all for this small but interesting topic.